Wow, this is a beautifully designed app that completely fits SoundCloud's style, so props. Aside from the improvements you've already suggested, I'd recommend having it so the "Play" button shows when the song is paused and the pause button shows when the song is playing as aside from the opposite way it currently is. I'll definitely be using this app in place of the site from now on, though :)
Oh, and it'd also be cool if there was a little mini floating player you could enable, like in iTunes :)

Unfortunately I'm still in review in the App Store. Not sure what I will do next with the App, but I welcome feedback. I will probably built in better playback queuing (queue track up next) and better Soundcontrol (AirPlay, 2x support, maybe EQ).

What this has over all of the other Soundcloud players for macOS is that this is natively built (I think), so the performance on this thing is excellent. Almost no CPU utilization (2- 3% on my MacBook Pro) and minimal memory footprint. Compare that with the alternatives that are built on Electron.
I'll be using this as my daily Soundcloud client starting right now. Excited to see where this goes. You should start charging for this immediately so that you're motivated to continue improving it. Who knows, you do this right and maybe Soundcloud cobbles together their coins to buy you and make this their official macOS client, which I think they really do need.